The quest for a deer airgun

[theairgunman]

Deer season is coming faster than I'd like to admit (7 months away). The good news is my quest for an airgun suitable for deer hunting is becoming more of a reality than something to shoot for. Tonight, I built a airgun almost like my air pistol, just bigger. The air chamber is 12" length of 3/4" type L copper pipe and the barrel is a 17" of 1/2" type L copper pipe. The piston is fully serviceable and the airgun itself would be easy to repair in the field if needed. In this configuration, it will produce 54 fpe at 400 psi firing a .54 cal roundball. If I triple the volume of the air chamber and increase the barrel length to 36", the muzzle energy will theoretically jump to 122 fpe, enough to do the job I need it to out to 45 yards. If I use a spring actuated ball valve like in my ball valve airgun to pilot the piston valve, it might even be a bit more powerful. This will give me a normal firearm trigger pull, a very desireable characteristic.
In the mean time, it is fun to have a airgun 22" long that can push 54 fpe! I'm thinking of adding a stock built from copper pipe to function as an airtank, hopefully giving me 4 or 5 shots before needing to repump. Instead of using .54 cal RB, a 1/2" ball bearing would shoot at 419 fps, or nearly 51 fpe. Any wild game coyote sized or smaller will quake at the sight of me 

[Pellethuntr]

 Hummm sounds like a thought. They only problem you will have is getting that .54 cal ball through a deers hide and ribs. They are very, very thick and the hide and hair can suck up a lot of energy. I would try shooting it at an untaned deer hid with the hair still on it If it goes through that then I would try 2 and so on and so on until you stop it.

[theairgunman]

A road kill deer sure would come in handy  I read somewhere that some guys actually tested small caliber air rifles on a road killed deer to see if you could effectively brain one with a .177 or .22 airgun. They concluded that it is possible with proper shot placement, but definitely didnt recommend it. Of course, it looks like my airgun will be a smoothbore, so a boiler room shot is the only way to go.
Actually, I bought the parts today to build a different valve that will allow me to use interchangeable barrels and air chambers. The parts only cost $7 and should easily outperform a sprinkler valve. Not to mention, it will handle 3 to 4 times the pressure.  Using a .72 roundball, GGDT predicts this design will produce nearly 200 fpe. It will also have a thornily stopping power of 80, so it should be more than adequate to put a deer down (recommended is a 50 on whitetail). I'm thinking that it will produce a massive wound channel, be capable of crushing ribs, and damaging the lungs and heart enough to provide a clean kill for an airgun. Much better than the .54 I was thinking of last night. Here is an article from a guy who has done a lot of airgun hunting: http://www.americanairgunhunter.com/deertracks.html. It is this article that suggests to me the effectiveness of a larger caliber as opposed to the .45 to .50 range they are using. He's got a video of the hunt on his site too!
My goal is to take a small doe within 25 yards. All of my homemade airguns can shoot at least a 2" to 3" group at that range with a unsupported pvc barrel. The copper barrel I plan to use will be far more rigid and should be able to shoot even tighter. The last deer I shot was only 10 paces from me, I stalked him on foot and brought him down with a 30-30.  As a precaution, I'll have my SKS in case I need any followup shots, or bring my buddy with his AR15. A buddy would be nice to do some filming as well...

[theairgunman]

OK, I've got the massive .72 cal built, just have to build a better piston. The one I cast last night out of hot melt glue failed under 200 psi! It actually got sucked through a .625" hole. The piston is .785"! I'm going to cast one out of bondo and use a neoprene washer for the sealing face.

[theairgunman]

I've got the Bondo piston cast, it works like a charm up to 150 psi. After that, the sealing face slips into the barrel. I think a small washer will fix that. At any rate, this sucker is scary at 150 psi! I shot 5 3/8" slingshot bearings, kinda like a load of buckshot. They nearly went all the way through my backstop at 15'. I'm going to have to do my high pressure tests out in the country. They collectively had 80 fpe, or 16 fpe each. As long as I can get my high pressure sealing issues fixed, I think I finally have my deer hunting airgun! Now I've got to get a .72 roundball scissor mold from track of the wolf. I have about 40 pounds of lead, which will make about 500 roundballs of that size. I definitely will trap all my target practice so I can recast, they sure use up a lot of lead.
To keep up my lead supply, I pick up every tire weight I find in parking lots and when I fish, I keep a look out for sinkers lying around. You'd be amazed how much you can collect and it brings shooting costs way down.

[Pellethuntr]

 Sounds interesting you will have to film it for me so I can see the power first hand. Sorry I haven't bee posting I was on a turkey hunting trip.

[theairgunman]

That small washer worked, I've tested it up to 375 psi, and it held air perfectly for an hour at that pressure. Dry firing at that pressure is absolutely deafening! Thank goodness for deaf old people living next door to me. lol How has turkey season been going for you? We got a lot of rain during our season, and I really havent heard anyone bragging, so I think it kinda stunk this year here.

[Pellethuntr]

 Me and my dad didn't get any but we sure called in a lot. My older cousin and his dad got 3 while we were on our trip. almost 400 psi!!! That's awesome when are you going to video it in action???

[theairgunman]

I've been so busy lately and when I've been off, it has been storming outside. Talk about impossible to shoot any video footage. I'm going to try to get out tomorrow and do some shooting. I've done some low power shooting in my garage for kicks. I found it will shoot an empty 12 gauge wad at 75 psi right through a soda can and cardboard box. 

[Pellethuntr]

 Cool sound like you might be getting close to the power you need.

[theairgunman]

I got some video footage, the airgun wasnt quite as powerful numerically as I'd hoped  That being said, at 300 psi, it was putting out 150 fpe! Between my quickly hobbled together sights, the heat, and gnats buzzing in and out of my eyes, ears, and nose, it was hard to get any footage worth assembling into a youtube video. lol I really need to invest in a regulated hpa tank and 3 stage pump. That shock pump takes too much! For fun, I'm thinking about building a stirrup pump in the mean time. If it works, I'll probably build my own air system around it instead of investing in the more expensive commercial stuff.

[Pellethuntr]

 Sounds like a good idea... 150 fpe wow that's not bad.

[boar]

this sounds like a intresting project Id sure like to see an update when you get time

Boar

[Pellethuntr]

 Right now me and airgunman are in kind of a friendly competition to see who can make the first airgun that is capable of shooting deer and to be the first to shoot a deer with it...

[boar]

how is yours workin out?

Boar